The present invention relates to a liquid ejecting apparatus that ejects liquid droplets such as ink from a liquid ejecting head onto a sheet.
As general liquid ejecting apparatii, ink jet printers that perform a printing process on a sheet by moving a liquid ejecting head (ink jet head) and ejecting ink droplets relative to a sheet of printing material such as a paper sheet are known.
In these ink jet printers, a phenomenon known as cock ring may occur in a print process. Specifically, cock ring occurs when a paper sheet is swollen with ripples due to ink droplets ejected onto the paper sheet. When cock ring occurs, the paper sheet may get dirty from contact with the print head or a paper jam error may occur.
Thus, a printing apparatus having a transport mechanism that sucks the paper sheet to a platen side by sucking the inside of a vacuum belt having a plurality of suction ports formed therein and transporting the paper sheet with the paper sheet adsorbed to the vacuum belt is known (for example, see Japanese Patent No. 3195792).
In addition, a printing apparatus that transports a paper sheet in a state that the paper sheet is pressed to endless belts by arranging a plurality of the endless belts having a thin and long shape and sucking air from an air suction port disposed between the endless belts is also known (for example, see Japanese Patent No. 2902150).
However, in the printing apparatus having a vacuum belt, the paper sheet may be swollen due to cock ring that occurred on the paper sheet in spots other than suction ports of the vacuum belt. In such a case, an increase of the number of the suction ports or a method of disposing the suction ports may be considered. In order to suppress the cock ring, a very strong suction force is needed. However, when the suction force is increased, a friction force between the vacuum belt and a belt receiving part increases to increase a transport load. Accordingly, it is difficult to smoothly transport the paper sheet with high precision. In addition, since a suction device that is large and expensive is needed, the costs increase. In addition, when the paper sheet is thin, ripples are generated from the increased suction force and the printing quality is deteriorated.
In the printing apparatus in which air suction ports are disposed in the platen located between the plurality of endless belts having a thin and long shape, the paper sheet on which the cock ring has occurred is adsorbed to the air suction ports to generate friction. Accordingly, it is difficult to smoothly transport the paper sheet with high precision. In such a case, it is preferable that the suction ports are disposed far from the paper sheet with respect to the upper face of the belt, in consideration of the cock ring of the paper sheet. However, in that case, it is difficult for the suction force in the air suction port to act upon the paper sheet, and the paper sheet cannot be drawn sufficiently. Accordingly, contact between the paper sheet and the print head and the paper jam error cannot be prevented sufficiently.